PROJECT SUMMARY/ABSTRACT This application builds upon the International Tobacco Control (ITC) Policy Evaluation Project's ongoing longitudinal panels of cigarette smokers and recent ex-smokers and extends to regular users of vaporized nicotine products (VNPs) (e.g., products like e-cigarettes). This Project assesses trajectories of the use of VNPs and their interactions with tobacco products, and, in collaboration with Project 3, which assesses non- smoking youth, to evaluate how VNPs and smoked tobacco product regulatory policies differentially influence tobacco and nicotine use behaviors in three countries ? the United States (US), England (EN), and Canada (CA). These three countries were selected for study because they have similar smoking rates and share similar histories of cigarette product regulations but have divergent policies regulating VNPs. This study will involve 10,967 adults aged 18 and older who will answer a 40-minute web survey at three points in time, 18 months apart. The survey, patterned after the ITC tobacco surveys, will include measures of smoking behavior, VNP awareness, trial use, regular use, reasons for VNP use, psychosocial mediators and moderators of continued use versus quitting for cigarettes and VNPs, and policy-relevant measures pertaining to smoking and VNP use, specifically: 1) product related regulations such as licensing, nicotine content, packing requirements, flavor restrictions, and manufacturing standards; 2) price and taxation; 3) place related restrictions such as smoke-free/vapor-free laws; and 4) promotional controls such as limits on advertising. There are three aims: Aim 1: To describe how the patterns of VNP and cigarette use differ among smokers and recent ex-smokers both over time and between important sub-groups (e.g., age groups, gender, income, those planning to quit smoking, nicotine dependence level), in particular whether the interactions between VNP and cigarette use vary across the three countries. Aim 2: To examine how differences in tobacco control and VNP policies between and within the US, EN, and CA are related to differences in the patterns of VNP and cigarette use. In particular, when policies on VNPs and/or cigarettes change in a country, this study will evaluate how these policy changes impact the use of VNPs and cigarettes in comparison to countries where no policy change has occurred. Aim 3: To contribute new information on the methods for monitoring health behaviors such as VNP use by comparing characteristics of the online samples recruited in this study with samples collected by conventional survey methods (e.g., PATH Household survey and other national surveys in EN and CA); and to explore the extent to which the behavior of the self-identified early adopters of VNPs (i.e., regular users who have used VNPs for some years) can provide useful indications of the behavior of the broader sample of adult smokers and hence, the mainstream population.